<div class="container mb-4">
  <nav class="navbar navbar-expand-lg navbar-light bg-light">
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarToggler_kh" aria-controls="navbarToggler_kh"
      aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <a class="navbar-brand" href="#">客户服务</a>
      <div class="collapse navbar-collapse" id="navbarToggler_kh">
      <ul class="navbar-nav mr-auto mt-2 mt-lg-0">
        <li class="nav-item active">
          <a class="nav-link" href="#">首页 <span class="sr-only">(current)</span></a>
        </li>
        <li class="nav-item">
          <a class="nav-link" href="#">链接</a>
        </li>
        <li class="nav-item">
          <a class="nav-link disabled" href="#">未启用栏目</a>
        </li>
      </ul>
      <form class="form-inline my-2 my-lg-0">
        <input class="form-control mr-sm-2" type="search" placeholder="搜索" aria-label="Search">
        <button class="btn btn-outline-success my-2 my-sm-0" type="submit">搜索</button>
      </form>
    </div>
  </nav>
</div>
